How Sleep Apnea Is Linked To Chronic Kidney Disease

As we know from the old song, “The toe bone’s connected to the foot bone, the foot bone’s connected to the leg bone….”, and so on. Our bodies are indeed vastly interlinked inner landscapes, each like an eco-system, with changes in one part potentially affecting many others at a distance.

One of the clearest examples of this is the way a condition like sleep apnea can end up having harmful effects on our kidneys. How can poor breathing in our sleep possibly affect an organ in charge of producing urine by its constant ‘filtering’ of blood? The connections are intriguing indeed.

When our very relaxed throat tissues collapse and narrow the breathing passageway at night, as they do in obstructive sleep apnea (OSA), there are two primary effects.

  • One is that we slip into a condition known as hypoxia, meaning that our blood becomes literally “under-oxygenated.”
  • The other is that our sleep becomes fragmented with frequent, brief awakenings, even though one is typically unaware of this.

This barely conscious level of sleep disruption is responsible for the degree of day time sleepiness – even exhaustion – which many sleep apnea sufferers endure, despite spending seemingly enough time in bed. However, this disruption also activates a subset of our nerves called the sympathetic nervous system. This network is involved in non-voluntary, automatic responses to changes in our bodies. These nerves cause the adrenal glands to release epinephrine, known commonly as adrenalin, which we correctly associate with being a bit on edge – the “butterflies in the stomach” feeling.

Adrenalin affects hormones from the kidneys and elsewhere that are involved in maintaining blood pressure – a key job of the kidneys. Chronic low-level stimulation of these hormones has several results. As might be expected, one of these is a rise in blood pressure. This leads to an over-filtration of blood in the kidneys and an increase of scar-like fibrous tissue there. Over time, these changes can lead to leakage of useful proteins into the urine and, ironically, an enduring under-filtration of blood by the damaged kidneys. These are hallmarks of kidney failure.

The low levels of oxygen seen in sleep apnea, the hypoxia, have a different set of effects that unfortunately lead to the same end result for the kidneys. In this case, recurring hypoxia over the months and years leads to inflammation of the inner lining of our blood vessels, called the endothelium. As blood vessel function diminishes, the kidneys again respond with less filtration of the blood yet simultaneous leakage of proteins into the urine, known as proteinurea.

So, the throat muscles are connected to the kidneys by way of the blood and the nervous system – no bones about it. And OSA has other bad effects as well. Fortunately, there are fixes for sleep apnea that sufferers are urged to look into. The most common is the continuous positive airway pressure (CPAP) device with its light-weight mask. Those not caring for this can look into mouthpieces, in consultation with both their doctor and dentist. There is even a surgical option.

Yet be advised that more serious cases of OSA may not be treatable with some of these options. Diagnosing sleep apnea itself as well as its severity is by doing a sleep study – something you don’t have to study for, just sleep, and which insurance usually covers. Even though we don’t think much about our kidneys, it’s a sure bet that we want them to be ‘happy’ and healthy!

One thought on “How Sleep Apnea Is Linked To Chronic Kidney Disease

  • November 22, 2012 at 4:52 am

    I was very surprised that throat muscle is connected to kidney, which i learned from this
    Article & about apnea which was very informative.


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